The AFIT Gross Motion Control Project

The objective of the Gross Motion Control project at the Air Force Institute of Technology (AFIT) Robotic Systems Laboratory is to investigate alternative control approaches that will provide payload invariant high speed trajectory tracking for non-repetitive motions in free space. Our research has concentrated on modifications to the model-based control structure. We are actively pursuing development and evaluation of both adaptive primary (inner loop) and robust secondary (output loop) controllers. In-house developments are compared and contrasted to the techniques proposed by other researchers. The case study for our evaluations is the first three links of a PUMA-560. Incorporating the principals of multiple model adaptive estimation, artificial neural networks, and Lyapunov theory into the model-based paradigm has shown the potential for enhanced tracking. Secondary controllers based on Quantitative Feedback Theory, or augmented with auxiliary inputs, significantly improve the robustness to payload variations and unmodeled drive system dynamics. This paper presents an overview of the different concepts under investigation and provides a sample of our latest experimental results.